In the refining industry every attempt is made to extract the maximum usable petrochemical product from the crude oil retrieved from deep within the earth or underseas. It would be fortunate to have a pure sweet product emerge, but this is very seldom the case. More often than not, the crude oil emerges partly as an emulsified mixture of oils, waxes, tars, salt and mineral laden water, fine sands and mineral particulates. Upon storage at the well and refinery sites, some natural settling and stratification occurs, but an intractable emulsion of oil and water and flocculate minerals remains to be dealt with. This waste or slop oil remains as a substantial environmental detriment and represent lost income from recoverable refinery feedstock. Among the many chemical and physical separation techniques, those that act to separate oil molecules from water molecules at their boundary interface with economy serve the oil recovery industry best.
Physical separation techniques employ conductive heating to reduce surface tension at the oil and water boundary interface and centrifuging to separate the less dense oil from water. In those situations in which the oil contains a large number of polar molecules with a hydrophilic (water loving) end and a hydrophobic (water hating) end, reduction of surface tension by direct heating alone will not suffice. And under those conditions in which complex organic compounds increase the density of the oil fraction to nearly that of water, the centrifuge relying on the difference in component densities, will fail to completely separate the components.
Chemical additives used as emulsion breakers often present an economic burden and additional contaminated water disposal problem. In most situations a combination of physical and chemical means are required.
Laboratory and field tests have proven that the application of radio frequency (RF) microwave energy to oil-water emulsions will result in separation at the molecular level to an advantage over other methods. It is believed that the oil-water interface bond is broken as the RF energy agitates the water molecule, a highly polar molecule that spins and twists rapidly in the oscillating radio frequency field. In a similar fashion, the hydrophilic polar end of the oil binding molecules are vibrated most by the radio frequency field. This shearing effect aids in the coalescence of oil droplets separated from the water droplets and the ultimate breaking of the emulsion. The vibration at the polar interface creates localized heating to further aid the separation of the constituents.
The present invention details an apparatus designed to effectively apply microwave radio frequency energy to a pumped stream of hydrocarbon and water emulsion with the maximum absorption of the radio frequency energy in a multimode resonant reentrant microwave cavity. Dual opposing emulsion flow chambers with a centrally supplied microwave waveguide form a double ended resonant chamber with multiple RF energy reflections to effectively treat the flowing emulsion. The emulsified feedstock enters into the bottoms of both flow chambers and exits from the top having been heated by and treated with microwave radio frequency energy.